Want proof? Emmett grabs a half gallon of skim milk from his kitchen refrigerator, then walks to the cupboard and fetches a medium-size Reese's Peanut Butter Cup.

Check the respective labels: A cup of skim milk contains 18 grams of fat versus only 7 grams for that chunk of candy.

FOR THE RECORD - An article in yesterday's Health & Science section that compared the nutritional content of skim milk and candy included incorrect information. A cup of skim milk contains about 12 grams of sugar, and a medium Reese's peanut butter cup contains 7 grams of sugar.The Sun regrets the error.

"There's sugar in milk products," he explains. "It's called lactose."

Emmett has just written a book, Turning Back the Hands of Time, in which he waxes at length about lactose and other simple sugars. They're comprised of smaller-than-normal molecules that quickly get absorbed into the bloodstream and deposited in the body's fat cells. They're the building blocks of love handles and jelly thighs.

In his book he also extols the virtues of eating lean proteins and complex carbohydrates while avoiding bread, pasta and even fruit (a natural source of those troublesome simple sugars).

According to Emmett, diet and nutrition are 80 percent of the prescription for healthy living, but precious few Americans bother to eat wisely.

"We are a nation of fat slobs," he writes.

The other 20 percent of Emmett's personal secret to success involves weight training, as evidenced by all the hardware on display inside his home gym - including that 2004 Mr. Maryland Masters Champion trophy for his 40-and-over age group.

He's got a highly developed torso that resembles a topographical map, with its winding-river veins and mountainous pectorals.

Emmett works out three or four times a week, often alongside his wife, Margie, a pediatric dentist who sports a chiseled physique of her own.

"I think shoulders and abs are probably my best components," says John, as he bangs out a few sets of two-arm curls, Popeye biceps bulging. "My hamstrings are not very good."

Most people would, of course, be happy to have those hamstrings. But, then, most people don't spend weekends posing half-naked for bodybuilding judges or feel sluggish if their body fat creeps beyond 5 percent.

"My family never ate fried foods," says Margie, who is busy grinding away on the leg-press machine. "Everything was baked and broiled."

She met her husband at University of Maryland Dental School and takes credit for turning John on to the wonders of nutrition. In fact, Margie still teases him about eating chipped beef on toast as a child.

"I finally understood why I grew up with indigestion," says John, chuckling, as he moves on to a round of triceps pushdowns.

Emmett grew up in the Baltimore area and took an interest in weightlifting in school after seeing a Charles Atlas ad in a magazine. It was only about six years ago, however, that he took the plunge into serious body sculpting. He can be passionate about fitness.

Ellen Lavine recalls an evening in December 2003 when the Emmetts invited her and her husband over for dinner. She's an avid athlete and always considered herself to be in top shape - until John got out his fat-measuring calipers and found some room for improvement.

"John is extremely disciplined and rigid in terms of what he will and will not eat," says Lavine. "I vacillate between thinking he's incredible and incredibly crazy. ... But what he's doing absolutely works. If you eat right, lift weights and do cardio, you will get results."

Neighbor Tim Rhode is co-owner of Maryland Athletic Center in Timonium. He bought six copies of Turning Back the Hands of Time and made "a subtle shift" in his lifestyle: having salad instead of a sandwich for lunch, eating more chicken and fish.

"I've seen a lot of philosophies come and go. His approach is so common sense," says Rhode. "Since Jan. 1 I've lost 14 pounds. It's just from eating cleaner."

The physical benefits of living cleaner ricochet off the mirrored walls of the Emmetts' gym. Everywhere you look, there are images of ripped muscles and taut tummies. Margie has sidled over to the lat machine. She especially likes back exercises.

"I think that's because of my work," says Margie, who spends most of her day hunched over the open mouths of children, filling cavities.

John admits being partial to bench presses. "Probably my favorite day is working my chest."

He dreads doing leg exercises, and not entirely without reason. A couple of years ago he was doing squats with 505 pounds when he momentarily lost focus: The bar slipped off the rack and came crashing down on his right shinbone.

The next day, a rest day, he went to the doctor and got fitted with a walking splint and crutches for his broken leg.

Better-living tips

Dr. Emmett's Fountain of Youth:

In Turning Back the Hands of Time, dentist-bodybuilder John Emmett explains how diet and exercise can shave years off the biological clock. Among his better-living suggestions:

Drink at least two quarts of water a day. "Nothing," says Emmett, "is more vital to good health."

Every day Emmett gets a half-hour of cardiovascular exercise, either running or hopping on his elliptical trainer. Do your cardio training in the morning. It speeds up the body's metabolic rate and will help you burn more fat throughout the day.

Weight training isn't just for men. In fact, it may be most important for women over 40. Resistance training increases bone density and can help prevent osteoporosis.

Read food labels. Beware any list of ingredients that includes sugar, saturated fats and high levels of sodium.

John Emmett's book sells for $14.95 on his Web site, www.nufitness.net, where you can also sign up for a free newsletter.